/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.thrift.meta_data;

import java.util.HashMap;
import java.util.Map;

import org.apache.thrift.TBase;
import org.apache.thrift.TFieldIdEnum;

/**
 * This class is used to store meta data about thrift fields. Every field in a a
 * struct should have a corresponding instance of this class describing it.
 * 
 */
public class FieldMetaData implements java.io.Serializable {
	private static final long serialVersionUID = 1L;
	public final String fieldName;
	public final byte requirementType;
	public final FieldValueMetaData valueMetaData;
	private static Map<Class<? extends TBase>, Map<? extends TFieldIdEnum, FieldMetaData>> structMap;

	static {
		structMap = new HashMap<Class<? extends TBase>, Map<? extends TFieldIdEnum, FieldMetaData>>();
	}

	public FieldMetaData(String name, byte req, FieldValueMetaData vMetaData) {
		this.fieldName = name;
		this.requirementType = req;
		this.valueMetaData = vMetaData;
	}

	public static void addStructMetaDataMap(Class<? extends TBase> sClass,
			Map<? extends TFieldIdEnum, FieldMetaData> map) {
		structMap.put(sClass, map);
	}

	/**
	 * Returns a map with metadata (i.e. instances of FieldMetaData) that
	 * describe the fields of the given class.
	 * 
	 * @param sClass
	 *            The TBase class for which the metadata map is requested
	 */
	public static Map<? extends TFieldIdEnum, FieldMetaData> getStructMetaDataMap(
			Class<? extends TBase> sClass) {
		if (!structMap.containsKey(sClass)) { // Load class if it hasn't been
												// loaded
			try {
				sClass.newInstance();
			} catch (InstantiationException e) {
				throw new RuntimeException(
						"InstantiationException for TBase class: "
								+ sClass.getName() + ", message: "
								+ e.getMessage());
			} catch (IllegalAccessException e) {
				throw new RuntimeException(
						"IllegalAccessException for TBase class: "
								+ sClass.getName() + ", message: "
								+ e.getMessage());
			}
		}
		return structMap.get(sClass);
	}
}
